1. Field of the Invention
The present invention relates to an automatic warming-up apparatus and a method thereof in hydraulic system, and more particularly, to an automatic warming-up apparatus and a method thereof applied in various hydraulic systems which are equipped with an engine and a hydraulic pump driven by the engine, and controlled by a microcomputer.
2. Description of the Prior Art
The conventional hydraulic system is provided with an engine and a hydraulic pump driven by the engine, and operated by supplying a discharge oil of the hydraulic pump to one or a plurality of hydraulic actuators.
In such a system, since lubricant oil and pressurized oil are not warmed up enough right after starting the system, there has been problems that the overall system including the engine and the hydraulic components becomes overstrained when the load is acted on the hydraulic actuator. Accordingly, it has been usually warmed up for a certain amount of time right after starting the system.
The conventional warming-up methods in hydraulic system are disclosed in Japanese utility model laid-open No. 80-85329, No. 85-147852, and Japanese patent laid-open No. 85-119342, and No. 87-167922.
In general, these methods include the method in which the warming-up is performed until the operation can be done with 100% load by increasing manually the rotation speed of the engine or controlling the discharge pressure and the discharge oil amount of the hydraulic pump, and the method in which an instruction is given by a controller so that the engine is warmed-up until the appropriate number of rotation is reached and, at the same time, the discharge pressure and the discharge oil amount of the hydraulic pump are adjusted based on the allowable output of the engine which is determined by detecting the rack position of a fuel supply pump through a sensor.
However, the manual warming-up method has problem that it is not only inaccurate but toilsome, and the automatic warming-up method has problems of the difficult initial adjustment of the sensor for detecting the rack position, an aging due to the use for a long period, and a weak environmental durability since it is installed in the inside of the engine.